Quasi-phase-matched optical parametric oscillators in bulk periodically poled LiNbO_3

TLDR

Periodically poled LiNbO₃ preserves the low‑loss, high‑power handling of single‑domain crystals while enabling noncritical phase matching with the highest‑valued d₃₃ coefficient. The paper reviews progress in quasi‑phase‑matched optical parametric oscillators using bulk periodically poled LiNbO₃. The authors fabricate 0.5‑mm‑thick periodically poled LiNbO₃ crystals with uniform domains over a 15‑mm length via electric‑field poling. Optical parametric oscillators pumped by 1.064‑μm Nd:YAG lasers operate over 1.4–4 μm with temperature or period tuning, achieve a threshold as low as 0.012 mJ with a Q‑switched pump, and demonstrate a cw doubly resonant oscillator near 1.96 μm pumped by a 978‑nm diode laser.

Abstract

We review progress in quasi-phase-matched optical parametric oscillators in bulk periodically poled LiNbO3. Using the electric-field poling process, we can reliably fabricate 0.5-mm-thick crystals with uniform domain structures over a 15-mm length. Periodically poled material retains the low-loss and bulk power handling properties of single-domain LiNbO3, and quasi phase matching permits noncritical phase matching with d33, the highest-valued nonlinear coefficient. Optical parametric oscillators pumped by 1.064-μm pulsed Nd:YAG lasers have been operated over the wavelength range 1.4–4 μm with tuning by temperature or by quasi-phase-matched period. We have shown an oscillation threshold as low as 0.012 mJ with a Q-switched pump laser and pumping at greater than ten times threshold without damage. We have also demonstrated a cw doubly resonant oscillator near 1.96 μm pumped directly with a commercial cw diode laser at 978 nm.